— Lily, look, a crowd of birds are flying to our small yard.
— Just now, I threw some bread in the yard. They have come here for the food.
A:a group of
B:few of
C:millions of
①2个镁原子____; ②3个水分子____;
③氦气____; ④正三价的铝元素____。
请回答下列问题:
中华民族伟大复兴的“中国梦”就是我国人民的共同理想。我们的共同理想是( )